IMX8M Plus Wi-Fi issue

[joshua_jhan]

Hi All,

I try to bring the Wi-Fi on IMX8M Plus, using Azurewave CM276 M.2 card.

on Yocto 5.4.47_2.3.0, I can detect the PCIe device using command "lspci", but the Wi-Fi driver mxm_wifiex doesn't seem to support it

on Yocto 5.4.70_2.2.0, mxm_wifiex does seem support it (default Makefile : CONFIG_PCIE8997=y) ,but I can't detect the PCIe device, command "lspci" is null.

In the above test, I always use the image for the Alpha/Beta website: 

https://www.nxp.com/pages/alpha-beta-bsps-for-microprocessors:IMXPRERELEASES

and following the steps on IMX_YOCTO_PROJECT_USERS_GUIDE.pdf to building image, But the result is the same.

I checked the i.MX_Linux_Release_Note, Yocto L5.4.70_2.3.0 and L5.4.43_2.2.0 both support Azurewave CM276, and PCIe slot.

Who can help me to solve this issue.

Thanks,

[joanxie]

refer to the 5.4.70_2.3.0 release note:

For platforms using Azurewave CM276 (NXP 88W8997), after
booting, users need to load or modprobe moal first before
other operations. Otherwise, modprobe moal module may fail
after suspending resumes. This is a Wi-Fi module issue still
under checking.

did you modprobe first??

[joshua_jhan]

Hi joanxie,

Yes, I used command "modprobe moal mod_para=nxp/wifi_mod_para.conf" to load the wi-fi driver, but no any response.

So I check the PCIe device using command "lspci" , still no any response too.

But in the Yocto-5.4.47_2.2.0, command lspci can detect the Azurewave CM276, like as below log.

NXP i.MX Release Distro 5.4-zeus imx8mpevk ttymxc1

imx8mpevk login: root
Last login: Wed Aug 19 15:03:14 UTC 2020 on tty7
root@imx8mpevk:~# uname -r
5.4.47-2.2.0+g5ec03d06f54e
root@imx8mpevk:~# lspci 
00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 (rev 01)
01:00.0 Ethernet controller: Marvell Technology Group Ltd. Device 2b42 (rev 11)

[marcelziswiler]

Please note that NXP BSP 5.4.70_2.3.0 only supports PCIe on i.MX 8M Plus A1 silicon unless you revert the following commit:

https://source.codeaurora.org/external/imx/linux-imx/commit/?h=imx_5.4.70_2.3.0&id=47fcb66d3e1fd7102...

[joshua_jhan · Accepted solution]

Hi marcelziswiler, 

I revert this commit, PCIe slot and mxm_wifiex can work now.

What will be affected about this reverted? 

And how to check the chip version for my i.MX 8M Plus evk? A1? A0?

Thanks

[marcelziswiler]

> What will be affected about this reverted? 

I believe A0 silicon had some errata(s). I assume NXP would know all details.

> And how to check the chip version for my i.MX 8M Plus evk? A1? A0?

U-Boot should tell you upon boot. E.g. A1 silicon looks as follows:

U-Boot 2022.04-6.0.0-devel+git.74abe35dfc13 (Aug 31 2022 - 08:24:30 +0000)

CPU: i.MX8MP[8] rev1.1 at 1200 MHz
...

[joanxie]

for A0, to check the last letter of the part number, if B stands for A1 and A stands for A0, refer to the Mask Set Errata for Mask P33A:

ERR050442: PCIe: PCIe PHY can’t support Gen3
Description: PCIe Gen3 mode is not functional. A design defect has been identified in the PCIe PHY which prohibits Gen3 mode operation. PCIe is functional in Gen1 and Gen2 modes after applying SW
workaround.
Workaround: There is no workaround for PCIe Gen3 mode of operation. Fix planned for next silicon revision. SW workaround for PCIe Gen 1 and Gen 2 mode will be implemented in the BSP starting
Alpha release.

[marcelziswiler]

> I revert this commit, PCIe slot and mxm_wifiex can work now.

Congratulations!

> What will be affected about this reverted?

Good question. But, likely, one should just throw any early access A0 silicon stuff in the bin now.

> And how to check the chip version for my i.MX 8M Plus evk? A1? A0?

A1 silicon would print the following in U-Boot:

CPU: i.MX8MP[8] rev1.1 1800 MHz (running at 1200 MHz)

A0 silicon would still report rev1.0.